Americans and Europeans have become increasingly concerned to hear of members of their own countries who have turned away from Western society and joined extremist groups like the Islamic State of Iraq and the Levant, or ISIL. Reports that the ISIL killer of American journalist James Foley might have been a British national have fueled fears that terrorists could be living among friends and neighbors in Western nations.

Leech says that he believes that for his brother, the transition to radicalism did not come out of the blue. “He was probably vulnerable,” he said, “He was probably quite lonely. He definitely was on his own journey to make sense of the world and to find meaning in life. … He met some of these guys, and they sort of took him under their wing.”

Indeed, ISIL has capitalized on its appeal to lost youth and has taken to social media to enlist recruits. Leech believes that ISIL may even use Westerners for high-profile activities as a form of propaganda, particularly in the case of James Foley’s execution. “The fact that it was British guy holding a knife … What it’s saying is that, ‘You guys in Britain, this is your Islamic State too.’ ”

Although families must grapple with devastation and betrayal when confronted with their loved ones’ new allegiances, Leech says he has not lost his affection for Dart. Despite his stepbrother’s convictions, he says, “I absolutely love him.”